The invention relates generally to four stroke internal combustion engines and to arrangements for enabling engine starting by effecting partial decompression of one or more of the engine cylinders.
More particularly, in conventional construction, such engines include a cam shaft which is adapted to be supported by a cylinder head casting or member and to engage an appropriate number of rocker arms so as to control opening and closing of the inlet and outlet valves of a four stroke engine.
Still more particularly, the cam shaft is intended to periodically rotate a rocker arm so as to lift a valve from a normally closed, spring biased, position in seating engagement with an associated valve seat. Consequently, the rocker arm is actuated by the cam shaft when appropriate to displace the valve from the valve seat.
Retaining the exhaust valve in an open position for a longer or extended period of time than when the engine is normally operating will serve to provide at least partial decompression in the associated cylinder, thereby enabling easier starting. Discontinuance of the extended or additional period of time during which the valve is open will permit normal opening and closing of the exhaust valve to obtain normal engine operation.
Attention is directed to the following U.S. Patents.
______________________________________ U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 2,323,304 R. H. Bowman July 6, 1943 2,850,002 J. Hovel September 2, 1958 3,223,076 H. Isoda December 14, 1965 3,314,408 A. P. Fenton April 18, 1967 3,342,169 Farny, et al. September 19, 1967 3,362,390 F. B. Esty January 9, 1968 3,381,676 K. W. Campen May 7, 1968 3,395,689 O. A. Kruse August 6, 1968 3,399,659 H. Isoda September 3, 1968 3,496,922 K. W. Campen February 24, 1970 3,511,219 F. B. Esty May 12, 1970 3,590,796 J. R. Harkness July 6, 1971 3,620,203 J. R. Harkness November 16, 1971 3,735,745 E. Hatz May 29, 1973 3,897,768 W. E. Thiel August 5, 1975 3,901,199 A. E. Smith August 26, 1975 3,981,289 J. R. Harkness September 21, 1976 4,018,203 A. Legros April 19, 1977 4,165,728 Matsumoto, et al. August 28, 1979 4,184,468 F. Freyn January 22, 1980 4,200,079 Darlington April 29, 1980 4,312,308 Slattery January 26, 1982 4,394,851 Greier, et al. July 26, 1983 4,453,507 Braun, et al. June 12, 1984 4,455,977 Kuczenski June 26, 1984 4,543,927 Luhn, et al. October 1, 1985 4,610,227 Nakano, et al. September 9, 1986 4,615,312 Tsumiyama October 7, 1986 4,615,313 Tsumiyama October 7, 1986 4,619,228 Liu October 28, 1986 4,648,362 Kastlunger March 19, 1987 4,651,687 Yamashita, et al. March 24, 1987 4,672,930 Sumi June 16, 1987 4,696,266 Harada September 29, 1987 4,790,271 Onda December 13, 1988 4,892,068 Coughlin January 9, 1990 4,898,133 Bader February 6, 1990 4,977,868 Holschuh December 18, 1990 ______________________________________
Attention is also directed to U.S. published patent application No. B558,251, filed by J. R. Harkness on Mar. 14, 1975.